Publications (72)
Optimizing Kilonova Searches: A Case Study of the Type IIb SN 2025ulz in the Localization Volume of the Low-Significance Gravitational Wave Event S250818k
Noah Franz, Bhagya Subrayan, Charles D. Kilpatrick +54
Kilonovae, the ultraviolet/optical/infrared counterparts to binary neutron star mergers, are an exceptionally rare class of transients. Optical follow-up campaigns are plagued by c…
Utilizing a global network of telescopes to update the ephemeris for the highly eccentric planet HD 80606 b and to ensure the efficient scheduling of JWST
Kyle A. Pearson, Chas Beichman, Benjamin J. Fulton +37
The transiting planet HD80606b undergoes a 1000-fold increase in insolation during its 111-day orbit due to it being highly eccentric (e=0.93). The planet's effective temperature i…
GROWTH on S190426c II: GROWTH-India Telescope search for an optical counterpart with a custom image reduction and candidate vetting pipeline
Harsh Kumar, Varun Bhalerao, G. C. Anupama +17
S190426c / GW190426_152155 was the first probable neutron star - black hole merger candidate detected by the LIGO-Virgo Collaboration. We undertook a tiled search for optical count…
Time-series and Phasecurve Photometry of Episodically-Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200 and ZTF
Josiah N. Purdum, Zhong-Yi Lin, Bryce T. Bolin +49
We observed Episodically Active Asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and have found that it is no longer active after its recent outburs…
The Jetted Tidal Disruption Event AT2022cmc: Investigating Connections to the Optical Tidal Disruption Event Population and Spectral Subclasses Through Late-Time Follow-up
Erica Hammerstein, S. Bradley Cenko, Igor Andreoni +14
AT2022cmc is the first on-axis jetted tidal disruption event (TDE) to be discovered at optical wavelengths. The optically bright nature of AT2022cmc presents an unprecedented oppor…
Type IIn Supernovae. I. Uniform Light-curve Characterization and a Bimodality in the Radiated Energy Distribution
Daichi Hiramatsu, Edo Berger, Sebastian Gomez +3
We present the largest uniform study to date of Type IIn supernovae (SNe IIn), focusing in this first paper on the multiband optical light curves of 490 SNe IIn. The sample, constr…
Discovery and confirmation of the shortest gamma ray burst from a collapsar
Tomas Ahumada, Leo P. Singer, Shreya Anand +54
Gamma-ray bursts (GRBs) are among the brightest and most energetic events in the universe. The duration and hardness distribution of GRBs has two clusters, now understood to reflec…
Optimizing Oil and Gas Acquisitions Using Recommender Systems
Harsh Kumar, Geneva Allison, Jehil Mehta +2
Well acquisition in the oil and gas industry can often be a hit or miss process, with a poor purchase resulting in substantial loss. Recommender systems suggest items (wells) that…
Impact of Guidance and Interaction Strategies for LLM Use on Learner Performance and Perception
Harsh Kumar, Ilya Musabirov, Mohi Reza +5
Personalized chatbot-based teaching assistants can be crucial in addressing increasing classroom sizes, especially where direct teacher presence is limited. Large language models (…
AT2023vto: An Exceptionally Luminous Helium Tidal Disruption Event from a Massive Star
Harsh Kumar, Edo Berger, Daichi Hiramatsu +10
We present optical/UV observations and the spectroscopic classification of the transient AT2023vto as a tidal disruption event (TDE) at z = 0.4846. The spectrum is dominated by a b…
Searching for gravitational wave optical counterparts with the Zwicky Transient Facility: summary of O4a
Tomás Ahumada, Shreya Anand, Michael W. Coughlin +49
During the first half of the fourth observing run (O4a) of the International Gravitational Wave Network (IGWN), the Zwicky Transient Facility (ZTF) conducted a systematic search fo…
Is Shapley Explanation for a model unique?
Harsh Kumar, Jithu Chandran
Shapley value has recently become a popular way to explain the predictions of complex and simple machine learning models. This paper is discusses the factors that influence Shapley…
Humanity's Last Exam
Long Phan, Alice Gatti, Ziwen Han +1144
Benchmarks are important tools for tracking the rapid advancements in large language model (LLM) capabilities. However, benchmarks are not keeping pace in difficulty: LLMs now achi…
"When Data is Scarce, Prompt Smarter"... Approaches to Grammatical Error Correction in Low-Resource Settings
Somsubhra De, Harsh Kumar, Arun Prakash A
Grammatical error correction (GEC) is an important task in Natural Language Processing that aims to automatically detect and correct grammatical mistakes in text. While recent adva…
Exploring The Design of Prompts For Applying GPT-3 based Chatbots: A Mental Wellbeing Case Study on Mechanical Turk
Harsh Kumar, Ilya Musabirov, Jiakai Shi +5
Large-Language Models like GPT-3 have the potential to enable HCI designers and researchers to create more human-like and helpful chatbots for specific applications. But evaluating…
Using Adaptive Bandit Experiments to Increase and Investigate Engagement in Mental Health
Harsh Kumar, Tong Li, Jiakai Shi +11
Digital mental health (DMH) interventions, such as text-message-based lessons and activities, offer immense potential for accessible mental health support. While these intervention…
Multi-Wavelength Analysis of AT 2023sva: a Luminous Orphan Afterglow With Evidence for a Structured Jet
Gokul P. Srinivasaragavan, Daniel A. Perley, Anna Y. Q. Ho +50
We present multi-wavelength analysis of ZTF23abelseb (AT 2023sva), an optically discovered fast-fading ( mag in days), luminous ( mag) an…
Algorithms for Adaptive Experiments that Trade-off Statistical Analysis with Reward: Combining Uniform Random Assignment and Reward Maximization
Tong Li, Jacob Nogas, Haochen Song +8
Traditional randomized A/B experiments assign arms with uniform random (UR) probability, such as 50/50 assignment to two versions of a website to discover whether one version engag…
GRB 230204B: GIT Discovery of a Fast Fading Afterglow Associated with an Energetic GRB from a Massive-Star Progenitor
Vishwajeet Swain, Varun Bhalerao, Harsh Kumar +19
We present a comprehensive multi-wavelength study of a bright gamma-ray burst GRB 230204B, analyzing both prompt and afterglow emissions. This GRB is highly energetic, with an isot…
FedProIn: Mitigating Client Drift for Learnable Prototypes in Federated Medical Imaging
Harsh Kumar, Tarun Kumar Garg, Vaanathi Sundaresan
Federated learning (FL) is severely hindered by statistical heterogeneity due to variations in scanners, acquisition protocols, and patient populations. Such non-IID data induces c…
A Sensitive Search for Supernova Emission Associated with the Extremely Energetic and Nearby GRB 221009A
Gokul P. Srinivasaragavan, Brendan O' Connor, S. Bradley Cenko +24
We report observations of the optical counterpart of the long gamma-ray burst (LGRB) GRB 221009A. Due to the extreme rarity of being both nearby () and highly energetic…
Multiwavelength Analysis of Six Luminous Fast Blue Optical Transients
Cassie Sevilla, Anna Y. Q. Ho, Nayana A. J. +43
We present multiwavelength observations and analysis of six luminous fast blue optical transients (LFBOTs) discovered in Zwicky Transient Facility (ZTF) survey data. We identified…
Chronocept: Instilling a Sense of Time in Machines
Krish Goel, Sanskar Pandey, KS Mahadevan +2
Human cognition is deeply intertwined with a sense of time, known as Chronoception. This sense allows us to judge how long facts remain valid and when knowledge becomes outdated. D…
Investigating the Role of Situational Disruptors in Engagement with Digital Mental Health Tools
Ananya Bhattacharjee, Joseph Jay Williams, Miranda Beltzer +6
Challenges in engagement with digital mental health (DMH) tools are commonly addressed through technical enhancements and algorithmic interventions. This paper shifts the focus tow…
A Near-IR Search for Helium in the Superluminous Supernova SN 2024ahr
Harsh Kumar, Edo Berger, Peter K. Blanchard +13
We present a detailed study of SN 2024ahr, a hydrogen-poor superluminous supernova (SLSN-I), for which we determine a redshift of . SN 2024ahr has a peak absolute magnitu…
SN 2024afav: A Superluminous Supernova with Multiple Light Curve Bumps and Spectroscopic Signatures of Circumstellar Interaction
Harsh Kumar, Peter K. Blanchard, Edo Berger +8
We present a comprehensive optical and near-infrared spectroscopic study of SN 2024afav - a hydrogen-poor superluminous supernova (SLSN-I) that peaks at -20.7 mag and exh…
Characterizing the Ordinary Broad-lined Type Ic SN 2023pel from the Energetic GRB 230812B
Gokul P. Srinivasaragavan, Vishwajeet Swain, Brendan M. O'Connor +39
We report observations of the optical counterpart of the long gamma-ray burst (LGRB) GRB 230812B, and its associated supernova (SN) SN 2023pel. The proximity () and high…
Cosmological Fast Optical Transients with the Zwicky Transient Facility: A Search for Dirty Fireballs
Anna Y. Q. Ho, Daniel A. Perley, Yuhan Yao +33
Dirty fireballs are a hypothesized class of relativistic massive-star explosions with an initial Lorentz factor below the required to p…
A very luminous jet from the disruption of a star by a massive black hole
Igor Andreoni, Michael W. Coughlin, Daniel A. Perley +78
Tidal disruption events (TDEs) are bursts of electromagnetic energy released when supermassive black holes (SMBHs) at the centers of galaxies violently disrupt a star that passes t…
When AI Gives Advice: Evaluating AI and Human Responses to Online Advice-Seeking for Well-Being
Harsh Kumar, Jasmine Chahal, Yinuo Zhao +4
Seeking advice is a core human behavior that the internet has reinvented twice: first through forums and Q&A communities that crowdsource public guidance, and now through large lan…
Radio Emission from the Infrared Tidal Disruption Event WTP14adeqka: The First Directly Resolved Delayed Outflow from a TDE
Walter W. Golay, Edo Berger, Yvette Cendes +10
We present detailed radio observations of the mid-infrared (MIR) tidal disruption event (TDE) WTP14adeqka. We detect rising radio emission starting years after the disc…
Large Language Model Agents for Improving Engagement with Behavior Change Interventions: Application to Digital Mindfulness
Harsh Kumar, Suhyeon Yoo, Angela Zavaleta Bernuy +6
Although engagement in self-directed wellness exercises typically declines over time, integrating social support such as coaching can sustain it. However, traditional forms of supp…
Multi-wavelength observations of multiple eruptions of the recurrent nova M31N 2008-12a
Judhajeet Basu, M. Pavana, G. C. Anupama +8
We report the optical, UV, and soft X-ray observations of the eruptions of the recurrent nova M31N 2008-12a. We infer a steady decrease in the accretion rate over the y…
The long-active afterglow of GRB 210204A: Detection of the most delayed flares in a Gamma-Ray Burst
Harsh Kumar, Rahul Gupta, Divita Saraogi +22
We present results from extensive broadband follow-up of GRB 210204A over the period of thirty days. We detect optical flares in the afterglow at 7.6 x 10^5 s and 1.1 x 10^6 s afte…
AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGN
Yael Dgany, Iair Arcavi, Grisha Zeltyn +18
The emission mechanism and host galaxy preference of optical/UV tidal disruption events (TDEs) are still not entirely understood. We present observations of the TDE AT 2022csn, whi…
James Webb Space Telescope Observations of the Nearby and Precisely-Localized FRB 20250316A: A Potential Near-IR Counterpart and Implications for the Progenitors of Fast Radio Bursts
Peter K. Blanchard, Edo Berger, Shion E. Andrew +23
We present deep James Webb Space Telescope near-infrared imaging to search for a quiescent or transient counterpart to FRB 20250316A, which was precisely localized with the CHIME/F…
The pair-instability origin of supernova 2023vbw
Daichi Hiramatsu, Edo Berger, Daichi Tsuna +18
Stars in the initial and carbon-oxygen core mass ranges of and M, respectively, with low metallicity are predicted to experience copious electron-pos…
Performance Characterization and Optimizations of Traditional ML Applications
Harsh Kumar, R. Govindarajan
Even in the era of Deep Learning based methods, traditional machine learning methods with large data sets continue to attract significant attention. However, we find an apparent la…
PermaFrost-Attack: Stealth Pretraining Seeding(SPS) for planting Logic Landmines During LLM Training
Harsh Kumar, Rahul Maity, Tanmay Joshi +4
Aligned large language models (LLMs) remain vulnerable to adversarial manipulation, and their reliance on web-scale pretraining creates a subtle but consequential attack surface. W…
Understanding Help-Seeking Behavior of Students Using LLMs vs. Web Search for Writing SQL Queries
Harsh Kumar, Mohi Reza, Jeb Mitchell +3
Growth in the use of large language models (LLMs) in programming education is altering how students write SQL queries. Traditionally, students relied heavily on web search for codi…
Demonstrating the Concept of Parallax with James Webb Space Telescope
Chow-Choong Ngeow, Harsh Kumar, Varun Bhalerao
We measured the parallax of the James Webb Space Telescope based on near simultaneous observations using the Lulin One-meter Telescope and the GROWTH India Telescope, separated at…
SN 2020sck: deflagration in a carbon-oxygen white dwarf
Anirban Dutta, D. K. Sahu, G. C. Anupama +7
We present optical UBVRI photometry and low-to-medium resolution spectroscopic observations of type Iax SN 2020sck spanning -5.5 d to +67 d from maximum light in the B-band. From t…
GROWTH on S190425z: Searching thousands of square degrees to identify an optical or infrared counterpart to a binary neutron star merger with the Zwicky Transient Facility and Palomar Gattini IR
Michael W. Coughlin, Tomás Ahumada, Shreya Anand +76
The third observing run by LVC has brought the discovery of many compact binary coalescences. Following the detection of the first binary neutron star merger in this run (LIGO/Virg…
When IIb Ceases To Be: Bridging the Gap Between IIb and Short-plateau Supernovae
Joseph R. Farah, D. Andrew Howell, Daichi Hiramatsu +13
Hydrogen-rich supernovae (SNe) span a range of hydrogen envelope masses at core collapse, producing diverse light curves from extended plateaus in Type II SNe to double-peaked Type…
Optical follow-up of the neutron star-black hole mergers S200105ae and S200115j
Shreya Anand, Michael W. Coughlin, Mansi M. Kasliwal +46
LIGO and Virgo's third observing run (O3) revealed the first neutron star-black hole (NSBH) merger candidates in gravitational waves. These events are predicted to synthesize r-pro…
A Detection of Helium in the Bright Superluminous Supernova SN 2024rmj
Harsh Kumar, Edo Berger, Peter K. Blanchard +8
We present extensive ultraviolet (UV), optical, and near-infrared (NIR) photometric and spectroscopic observations of the nearby hydrogen-poor superluminous supernova (SLSN-I) SN20…
Using Images to Find Context-Independent Word Representations in Vector Space
Harsh Kumar
Many methods have been proposed to find vector representation for words, but most rely on capturing context from the text to find semantic relationships between these vectors. We p…
Diagnosing and Repairing Persona Collapse in LLM Advice
Harsh Kumar, Karina Vold, Louis Tay +1
LLMs are increasingly used for personal advice on relationships, work, moral dilemmas, and crises. Post-training selects a stable, prosocial Assistant persona, but good advice requ…
Far-Ultraviolet to Near-Infrared Observations of SN 2023ixf: A high energy explosion engulfed in complex circumstellar material
Rishabh Singh Teja, Avinash Singh, Judhajeet Basu +13
We present early-phase panchromatic photometric and spectroscopic coverage spanning far-ultraviolet (FUV) to the near-infrared (NIR) regime of the nearest hydrogen-rich core-collap…
India's first robotic eye for time domain astrophysics: the GROWTH-India telescope
Harsh Kumar, Varun Bhalerao, G. C. Anupama +35
We present the design and performance of the GROWTH-India telescope, a 0.7 m robotic telescope dedicated to time-domain astronomy. The telescope is equipped with a 4k back-illumina…
Fast-transient Searches in Real Time with ZTFReST: Identification of Three Optically-discovered Gamma-ray Burst Afterglows and New Constraints on the Kilonova Rate
Igor Andreoni, Michael W. Coughlin, Erik C. Kool +32
While optical surveys regularly discover slow transients like supernovae on their own, the most common way to discover extragalactic fast transients, fading away in a few nights, i…
Human Creativity in the Age of LLMs: Randomized Experiments on Divergent and Convergent Thinking
Harsh Kumar, Jonathan Vincentius, Ewan Jordan +1
Large language models are transforming the creative process by offering unprecedented capabilities to algorithmically generate ideas. While these tools can enhance human creativity…
Astreaks: Astrometry of NEOs with trailed background stars
Kritti Sharma, Harsh Kumar, Harsh Choudhary +7
The detection and accurate astrometry of fast-moving near-Earth objects (NEOs) has been a challenge for the follow-up community. Their fast apparent motion results in streaks in si…
Lense-Thirring precessing magnetar engine drives a superluminous supernova
Joseph R. Farah, Logan J. Prust, D. Andrew Howell +10
Type I superluminous supernovae (SLSNe-I) are at least an order of magnitude brighter than standard supernovae, with the internal power source for their luminosity still unknown. T…
SN 2018hna: 1987A-like supernova with a signature of shock breakout
Avinash Singh, D. K. Sahu, G. C. Anupama +22
High cadence ultraviolet, optical and near-infrared photometric and low-resolution spectroscopic observations of the peculiar Type II supernova (SN) 2018hna are presented. The earl…
Supporting Self-Reflection at Scale with Large Language Models: Insights from Randomized Field Experiments in Classrooms
Harsh Kumar, Ruiwei Xiao, Benjamin Lawson +8
Self-reflection on learning experiences constitutes a fundamental cognitive process, essential for the consolidation of knowledge and the enhancement of learning efficacy. However,…
The Luminous, Slow-Rising Orphan Afterglow AT2019pim as a Candidate Moderately Relativistic Outflow
Daniel A. Perley, Anna Y. Q. Ho, Michael Fausnaugh +34
Classical gamma-ray bursts (GRBs) have two distinct emission episodes: prompt emission from ultrarelativistic ejecta and afterglow from shocked circumstellar material. While both c…
Efficacy of Galaxy Catalogues for following up gravitational wave events
Tamojeet Roychowdhury, Harsh Choudhary, Varun Bhalerao +6
The detection of gravitational waves (GW) by the LIGO-Virgo-KAGRA (LVK) network has opened up a new era in astrophysics. The identification of the electromagnetic counterparts of G…
The Fast, Luminous Ultraviolet Transient AT2018cow: Extreme Supernova, or Disruption of a Star by an Intermediate-Mass Black Hole?
Daniel A. Perley, Paolo A. Mazzali, Lin Yan +60
Wide-field optical surveys have begun to uncover large samples of fast (t_rise < 5d), luminous (M_peak < -18), blue transients. While commonly attributed to the breakout of a super…
Collapsars as Sites of r-process Nucleosynthesis: Systematic Near-Infrared Follow-up of Type Ic-BL Supernovae
Shreya Anand, Jennifer Barnes, Sheng Yang +41
One of the open questions following the discovery of GW170817 is whether neutron star mergers are the only astrophysical sites capable of producing -process elements. Simulation…
GROWTH on S190814bv: Deep Synoptic Limits on the Optical/Near-Infrared Counterpart to a Neutron Star-Black Hole Merger
Igor Andreoni, Daniel A. Goldstein, Mansi M. Kasliwal +49
On 2019 August 14, the Advanced LIGO and Virgo interferometers detected the high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that the event resulte…
Investigating the Effects of LLM Use on Critical Thinking Under Time Constraints: Access Timing and Time Availability
Jiayin Zhi, Harsh Kumar, Mina Lee
The impact of large language models (LLMs) on critical thinking has provoked growing attention, yet this impact on actual performance may not be uniformly negative or positive. Par…
Minutes-duration Optical Flares with Supernova Luminosities
Anna Y. Q. Ho, Daniel A. Perley, Ping Chen +74
In recent years, certain luminous extragalactic optical transients have been observed to last only a few days. Their short observed duration implies a different powering mechanism…
Gravitational Waves and Electromagnetic Transients
Akshat Singhal, Sourav Palit, Suman Bala +3
The advanced gravitational wave (GW) detector network has started {routine detection of } signals from merging compact binaries. Data indicate that in a fair fraction of these sour…
Transforming GenAI Policy to Prompting Instruction: An RCT of Scalable Prompting Interventions in a CS1 Course
Ruiwei Xiao, Runlong Ye, Xinying Hou +4
Despite universal GenAI adoption, students cannot distinguish task performance from actual learning and lack skills to leverage AI for learning, leading to worse exam performance w…
Kilonova Luminosity Function Constraints based on Zwicky Transient Facility Searches for 13 Neutron Star Mergers
Mansi M. Kasliwal, Shreya Anand, Tomas Ahumada +100
We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run. We searc…
Human Thinking under Plural LLM Assistance: Mathematical Problem Solving and Open-Ended Writing
Harsh Kumar, Jace Mu, Jonathan Vincentius +1
Large language models are changing not only the kind of assistance people receive, but also how that assistance is organized. Instead of working with a single general-purpose chatb…
Hydrogen-Poor Superluminous Supernovae in the Nebular Phase: Spectral Diversity Due to Ejecta Ionization as a Probe of the Power Source
Peter K. Blanchard, Edo Berger, Sebastian Gomez +6
We present a large sample of 39 nebular-phase optical spectra of 25 hydrogen-poor superluminous supernovae (SLSNe-I) and jointly analyze them with previously published spectra of 1…
In search of short gamma-ray burst optical counterpart with the Zwicky Transient Facility
Tomás Ahumada, Shreya Anand, Michael W. Coughlin +46
The Fermi Gamma-ray Burst Monitor (GBM) triggers on-board in response to 40 short gamma-ray bursts (SGRBs) per year; however, their large localization regions have made the…
Real-time Discovery of AT2020xnd: A Fast, Luminous Ultraviolet Transient with Minimal Radioactive Ejecta
Daniel A. Perley, Anna Y. Q. Ho, Yuhan Yao +29
The many unusual properties of the enigmatic AT2018cow suggested that at least some subset of the empirical class of fast blue optical transients (FBOTs) represents a genuinely new…
The Type I Superluminous Supernova Catalog I: Light Curve Properties, Models, and Catalog Description
Sebastian Gomez, Matt Nicholl, Edo Berger +25
We present the most comprehensive catalog to date of Type I Superluminous Supernovae (SLSNe), a class of stripped envelope supernovae (SNe) characterized by exceptionally high lumi…
The Nature of Optical Afterglows Without Gamma-ray Bursts: Identification of AT2023lcr and Multiwavelength Modeling
Maggie L. Li, Anna Y. Q. Ho, Geoffrey Ryan +29
In the past few years, the improved sensitivity and cadence of wide-field optical surveys have enabled the discovery of several afterglows without associated detected gamma-ray bur…